(To this day, we still cannot watch this knockout without mourning what could have been.)

Heading into his UFC debut against Eddie Sanchez at UFC 67, Mirko “Cro Cop” Filipovic was already considered by many to be the far and away best striker in the UFC’s heavyweight division, if not in all of MMA. His left high kick had become the thing of legend thanks to his devastating wins over Aleksander Emelianenko, Igor Vovchanchyn and Wanderlei Silva in PRIDE, to the point that it kinda-sorta became our slogan. And after he defeated Sanchez via a first round TKO set into motion by that very same kick, we figured it was only a matter of time before we saw “Mirko Cro Cop: UFC Heavyweight Champion” pasted on every UFC poster imaginable.

But as they so often do, the MMA Gods threw a wrench into our (and Mirko’s) plans at UFC 70: Nations Collide on April 21st, 2007 — seven years ago today. In a heavyweight title eliminator match that served as the evening’s main event, the Croatian special forces officer was paired against Gabriel Gonzaga, a Cro magnon-looking Brazilian who had scored three consecutive finishes (two TKO, one sub) in his first three UFC contests. Cro Cop was listed as over a 5-to-1 favorite across the board.

Any notion that the fight would be an easy win for Mirko was erased in the first round, however, as Gonzaga managed to take Filipovic down on multiple occasions and batter him with vicious elbows from on top for the majority of five minutes.

In perhaps the most dramatic twist of fate in MMA history, Gonzaga Cro-Copped Cro Cop with a head kick, sending him crashing to the mat with his ankle twisted hideously beneath him. The KO came with just 9 seconds left in the round, and to this day remains one of the most shocking and unexpected knockouts of all time. In fact, the knockout was incredible enough to land on the UFC’s “Ultimate 100 Knockouts” list at #3, behind only Barboza vs. Etim and Silva vs. Belfort.

The devastating KO would earn Gonzaga a shot at Randy Couture — who just so happened to be on hand for his brutal KO of Filipovic — with the heavyweight title on the line at UFC 74. Despite nearly ending Couture’s run in the same fashion as Cro Cop’s with a high kick in the first round, Gonzaga would suffer a third round TKO defeat to the legend and would go just 3-4 before being released by the UFC in 2010. A brief retirement would follow before Gonzaga returned to the UFC, where he has gone 5-2 since.